This invention relates to a microphone range finder, in particular, to a microphone system in which the relative position of a speaker to the microphone is determined and wherein compensation for said relative position are included to obtain an improved audio response.
There are two basic types of noise suppressing microphones known in the art:
(1) "Shotgun" microphones which are very directional; and
(2) "Close talking" or "Noise Cancelling" microphones which are omnidirectional but sensitive to sound originating from the immediate vicinity of the microphone only.
Both types of microphones operate poorly when the source of the sound (e.g. the person speaking) is not exactly where it is expected to be. The result is considerably reduced volume which must be compensated for in some way.
To compensate for the above short comings, present day systems employ automatic gain control amplifiers to provide appropriate gain in dependence upon the energy contained in a microphone signal. However, automatic gain control tends to clip the beginning of speech so that the words "hello", for example, is transmitted as "ello". Furthermore, automatic gain control tends to reduce the quality and fidelity of speech in instances where, for example, a speaker is situated far from the microphone whereby ambient noise emenating from nearby sources or from the microphone itself is introduced into and amplified by the microphone system.
A further disadvantage of present microphone systems which employ automatic gain control is related to situations in which several speakers--who may be moving about a room--are required to address an audience. Under such circumstances, the automatic gain control may be affected by the position of each speaker relative to the microphone, and individual automatic gain control for each speaker is not practicable.